The brutality of ISIS is agonizing, but if the organization’s deluded leaders think that the beheadings of two American journalists will cause the United States to back off, then they are even more detached from reality than they seem.

The Islamic State has shown itself to be among the worst specimens that mankind is capable of producing and, in that, it fairly shrieks for the United States, and the world, to respond with force. That response has begun, but a more comprehensive approach is needed.

Indeed, the savage beheadings of journalists Steven J. Sotloff, 31, and James Foley, 40, demand a regional and international response proportional to a terrorist organization that Defense Secretary Chuck Hagel described as an “imminent threat to every interest we have.” The organization, which has grabbed territory in Syria and Iraq, wants to create an Islamic caliphate whose goals will include international terrorism.

President Obama has been criticized for his slow response to ISIS, but his determination to first replace former Iraqi Prime Minister Nouri al-Maliki with a successor more willing to share power was, in the end, a wise move that may help to unite Iraqis against the threat. Once al-Maliki announced that he would depart, American air power helped Iraqis retake the critical Mosul dam and reclaim other territory lost to ISIS.

But that only twisted the tail of the tiger, and led to the beheadings first of Foley and, this week, of Sotloff. ISIS evidently believes that demonstrating its blood lust will prompt Americans and their government to shrink from the danger posed by the terrorists.

That can’t be allowed to happen, and Obama says it won’t. What the president needs to do, though, is to better explain the threat to the country, consult with Congress to win support for a broad-based response and enlist the support of the international community, especially from Middle Eastern nations that have the most to lose from the growth of ISIS, at least over the short term.

The situation is complicated by the grim fact that moving against ISIS will almost certainly bolster the criminal regime of Syrian President Bashar Assad, whom the United States has sought to remove in the face of Syria’s civil war.

It will be unfortunate if taking necessary action against ISIS benefits Assad, but the rise of ISIS is a broader threat that requires an immediate response, even if it conflicts with the goal of unseating Assad. If fighting ISIS means the United States and other nations must bomb ISIS strongholds in Syria, then that is what must be done.

It is, in some ways, a bitter moment for millions of Americans who had hoped, after almost 13 years of war, to pull back from the Middle East. But that’s not possible today. While no one is advocating the use of ground troops, American air power is precise and can clear the way for Iraqi ground troops to confront ISIS.

Indeed, a recent poll by the Huffington Post and YouGov shows that a majority of Americans – 60 percent – support airstrikes against ISIS in Iraq and Syria. Only 20 percent are opposed.

This country learned the hard way that it is mortally dangerous to ignore the threat of terrorists bent on bloodshed. This is a time for Obama to rally the country and the world to heed that lesson and deal with this threat now, not later.